Chitosan/Hyaluronic Acid/Zinc Oxide Carbohydrate-Based Nanocomposite Modulates Inflammatory and Functional Responses in β -Cell Spheroids

Zinc plays a critical role in β-cell physiology by regulating insulin storage, crystallization, and secretion. However, uncontrolled exposure to zinc oxide nanoparticles (ZnO-NPs) can cause cytotoxic and inflammatory responses. Here, we investigated whether incorporation of ZnO-NPs within a hydrated carbohydrate-based nanocoating modifies their short-term biological effects. Five chitosan/hyaluronic acid (Cs/HA) bilayers containing ZnO-NPs in the HA deposition layers were assembled on MIN6 β-cell spheroids. Physicochemical characterization supported the formation of continuous Cs/HA multilayers and incorporation of ZnO-associated domains. A cell-free alginate-capsule model showed size-dependent transport of FITC-dextran probes, with high relative permeability to 4-10 kDa dextrans and reduced permeability to 40-70 kDa dextrans. Compared with dispersed ZnO-NPs, multilayer-incorporated ZnO-NPs produced lower acute cytotoxicity, DCFDA fluorescence following tert-butyl hydroperoxide challenge, and macrophage-derived TNF-α secretion under the conditions tested. At a formulation concentration of 25 μg mL-1, ZnO-NP incorporation altered basal insulin secretion while maintaining glucose responsiveness and increased the abundance of transcripts associated with zinc transport and buffering. These findings establish a proof of concept that incorporating ZnO-NPs within Cs/HA multilayers changes their short-term presentation to β-cell spheroids and macrophages. Further studies are required to quantify ZnO retention and zinc release, establish long-term stability and function, and validate the platform using primary or human islet models.